多元(U,Zr, Nb)C燃料制备技术与性能机理研究  

Preparation Technology and Performance Mechanism of Multi-element (U, Zr, Nb)C Fuel

作　　者：吴学志[1] 魏国良[1] 郭骁 WU Xuezhi;WEI Guoliang;GUO Xiao(Reactor Engineering Technology Research Institute,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]中国原子能科学研究院反应堆工程技术研究所,北京102413

出　　处：《原子能科学技术》2024年第1期166-174,共9页Atomic Energy Science and Technology

摘　　要：多元(U,Zr, Nb)C燃料因具有熔点高、热导率高、低裂变气体释放率及优异的高温力学性能等优点,是目前大功率空间核推进反应堆选用燃料之一。本文采用碳热还原和液相烧结相结合的粉末冶金工艺制备多元(U,Zr, Nb)C燃料芯块,研究了工艺参数对烧结芯块反应动力学、相结构、导热性能和微观结构的作用机制和影响规律。结果表明:在1 800℃、50 MPa和1 h的烧结条件下,通过添加0.5%金属铀形成的液相烧结工艺制备得到芯块密度可达95.5%TD;当原料M/C(M为金属元素总量)摩尔比为1∶6.5时,可制备得到M/C比为1的正化学计量碳化物燃料;(U0.2,Zr, Nb)C的晶格常数比(U0.1,Zr, Nb)C的晶格常数略高;多元(U,Zr, Nb)C碳化物燃料芯块热导率与相成分、密度和温度均有关;芯块气孔分布较均匀,没有联通的开气孔存在,气孔尺寸在1~3μm。High thrust nuclear-powered spacecraft is the key technology for deep space exploration and low Earth orbit transportation in the future,the nuclear thermal propulsion system has the advantages of high specific impulse,high thrust,long operating life and repeatable start-up,which can provide reliable power support for future deep space exploration missions.Multi-element(U,Zr,Nb)C fuel is one of the selected fuels for high-power space nuclear propulsion reactors due to its high melting point,high thermal conductivity,low fission gas release rate and excellent high-temperature mechanical properties.In this paper,multi-element(U,Zr,Nb)C fuel pellets were prepared by powder metallurgy process combining carbothermal reduction and liquid phase sintering.The mechanism and influence of process parameters on reaction kinetics,phase structure,thermal conductivity and microstructure of sintered pellets were studied.The results show that according to the calculation of reaction thermodynamics,the carbothermal reduction temperatures for UO 2 and Nb 2O 5 are 2122 K and 1206 K at standard pressure,respectively;Under the sintering conditions of 1800℃,50 MPa and 1 h,the pellet density can reach 95.5%TD by adding 0.5%metallic uranium to form liquid phase sintering,liquid phase sintering accelerates the densification process of the pellets;When the raw material M/C(M is the total metal element)is 1∶6.5,the stoichiometric carbide fuel with M/C ratio of 1 can be prepared,using ZrC powders as raw materials can not only reduce the reaction temperature,but also reduce the difficulty of adjusting the M/C ratio of the reaction product;The lattice constant of(U 0.2,Zr,Nb)C is slightly higher than that of(U 0.1,Zr,Nb)C;The thermal conductivity of carbide fuel is related to phase composition,density and temperature;The thermal conductivity of(U 0.1,Zr,Nb)C and(U 0.2,Zr,Nb)C fuels increases with the increase of the content of uranium carbide,and the increase of Zr content is beneficial to the increase of the thermal conductivity of the pe

关 键 词：多元 核推进 燃料 碳热还原 液相烧结 

分 类 号：TL352.21[核科学技术—核技术及应用]